The present invention relates to a velocity-variation minimization control method for a robot and, in particular, to such a method suitable for application to a robot that performs painting or sealing work.
In general, a robot that performs painting or sealing work is required to move along a complex path both at high speed and smoothly.
Therefore, such movements are realized by minutely specifying details of velocity and path, and such specification is done by teaching the specified velocity and specified path to a robot arm or limb at a fine pitch. In other words, a smooth path is obtained by detailed specifications for each of a large number of short distances or each of a large number of short periods of time.
However, with this method, the algorithms required for teaching by detailed specification are complicated and hence the amount of calculation required increases, the necessary high velocities cannot be obtained, and velocity variations cannot be avoided.
For that reason, smooth path control using high-order functions has been proposed.
For example, Japanese Patent Laid-Open Number 62-72008 (1987) illustrates a fifth-order function method which can obtain a path in which variations with time in acceleration (second-order changes in velocity) are minimized, wherein (1) position at start and end points, (2) velocity vectors at start and end points, (3) acceleration vectors at start and end points, and (4) the time required to move between the two points, act as conditions for obtaining a path between two points.
However, with this method, the user must take into consideration factors such as control based on the robot's abilities when specifying the time taken to move between the two points, which is a scalar quantity, and there is a problem that the path itself and the movement velocity can vary with the specified value of the movement time.